Real-Time Clock Time Rewrite Validation for Vehicle Networks

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Solution Overview

Problem

Existing real-time clock systems struggle to accurately verify the legitimacy of time data rewritten from external sources, particularly failing to detect illegitimate time data that is not from the past, which can lead to improper system timing and reliability issues in vehicle-mounted networks.

Innovation Solution

A real-time clock device with an oscillation circuit, clocking circuit, and control circuit that compares present time data with time rewriting data to determine legitimacy, using a calculated allowable error based on clocking accuracy and reference time data to prevent illegitimate time data from being written.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If timestamp data is stored in nonvolatile memory before MPU enters sleep mode and compared with external time information upon wake-up, then legitimacy verification of external time data is improved, but illegitimate time data within the sleep period cannot be detected

Engineering Contradiction:

Improvelegitimacy verification of external time dataVSAvoiddetection accuracy of illegitimate time data

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent stores the present time data from the clocking circuit in nonvolatile memory before the MPU enters sleep mode. This preliminary action ensures that when the system wakes up, there is reference data available to compare against external time information, enabling detection of illegitimate time data that occurred during the sleep period.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where the clocking circuit continuously generates present time data, which is periodically stored in nonvolatile memory. Upon wake-up, this stored data is compared with newly acquired external time information, creating a closed-loop verification system that provides feedback on time data legitimacy.

Inventive Principle:

Principle #23Feedback

2Ease of operation

If external time data is acquired from network or satellite positioning system, then time initialization and periodical correction are enabled, but system is vulnerable to illegitimate time data injection

Engineering Contradiction:

Improvetime initialization and correction capabilityVSAvoidsecurity against illegitimate time data

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent performs preliminary action by storing the internal clock's present time data in nonvolatile memory before the system enters sleep mode or before acquiring external time data. This creates a reference point that enables subsequent verification of external time data legitimacy, preventing illegitimate time injection while maintaining ease of time initialization and correction.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces the clocking circuit's internal time data as an intermediary verification layer between the external time sources (network, satellite) and the system's timekeeping. This intermediary provides an independent reference that mediates the verification process, allowing the system to safely acquire external time data while protecting against illegitimate injections.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Speed

If present time data is continuously maintained by clocking circuit using oscillation signal, then real-time timekeeping is achieved, but vulnerability to illegitimate time rewriting increases

Engineering Contradiction:

Improvereal-time timekeeping responseVSAvoidresistance to illegitimate time rewriting

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent performs preliminary action by storing the clocking circuit's present time data in nonvolatile memory at specific intervals (before sleep mode, before external time acquisition). This creates checkpoints that enable later verification, allowing the system to maintain continuous real-time timekeeping while periodically verifying integrity to resist illegitimate rewriting.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuous operation of the clocking circuit to ensure uninterrupted real-time timekeeping. The useful action of time generation continues without interruption, while verification is performed at strategic points using the stored reference data, thus maintaining both continuity and security.

Inventive Principle:

Principle #20Continuity of useful action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Ensures accurate legitimacy determination of time data, preventing illegitimate time data from being applied, thus maintaining system timing reliability and security in vehicle-mounted networks.

Implementation Method 1

an oscillation circuit configured to generate an oscillation signal using a resonator

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS10727817B2Real-time clock device, electronic device, and vehicle

Publication Date: 2020.07.28 SEIKO EPSON CORP

AI summary

A real-time clock device includes an oscillation circuit configured to generate an oscillation signal using a resonator, a clocking circuit configured to generate present time data based on the oscillation signal, an interface circuit configured to receive a time rewriting request and time rewriting data for the present time data from an external device, and a control circuit configured to perform comparison processing of the present time data of the clocking circuit and the time rewriting data to determine whether the time rewriting data is legitimate.